Cathode ray deflecting circuit



Jam 30, 1940. K; 5 5 2,188,580

CATHODE RAY DEFLECTING CIRCUIT Original. Filed March 26; 1934 PatentedJan. 30, 1940 Nir mes cA'rnonE RAY DEFLECTING cmc rr, 1

Kurt Schlesinger, Berlin, Germany, assignor, by mesne assignments, toLoewe Radio, Inc., a corporation of New York i Original applicationMarch 26', 1934, Serial No. v

717,307, now Patent No. 2,077,271, dated April. 13, 1937. Divided andthis application November 3, 1936, Serial No. 108,950.' In Germany March29, 1933 3 Claims; (01. 250-275 the space between the middle plate andthe lower plate, and then leaves this space, in the state of rest,parallel to the direction of its entry into the system. After being bentinto the space .between the middle plate and the lower plate, thecathode ray undergoes scanning deflections in this latter space. In thisarrangement the middle plate is maintained at a constant potential,whilst the full'scanning deflection potential is applied to the lowerdeflecting plate. In this arrangement considerable potentials (of theorder of about 400 volts) are required fora complete modulation.

The object of the invention is an additional makes it possible tooperate with considerablyv lower scanning potentials.

According to the invention, the middle plate is divided into twocompletely independent parts, both of which have the same D. C.potential (positive in relation to the two outer plates).

The scanning potential is supplied simultaneously and in phaseopposition to the one outer plate and'to the part of the middle platedirected towards the luminous screen.

In this manner it is possible to perform fullrange control with half thepotential otherwise required.

A form of embodiment of the invention is illustrated by way of examplein the single figure of the drawing.

Herein i is the anode of the Braun tube, 2 a deflecting plates systemwith the two outer plates 3 and 4 and the inner plate comprising the twoparts 5 and 6. The plates 3 and 4 are maintained at anode (earth)potential as regards D. C. conditions, whilst the middle plate ispositively biased to such extent in relation to the plates 3 and '4 thatthe ray entering the space between the plates 3 and 5 is bent into thespace between: the plates 4 and 5, and emerges from this space in itsstate of rest parallel to the direction of its entry but displaced in,relation thereto to the extent of a few millimetres. The

plates 5 and B are connected with each other over a high ohmicresistance 1 of about 10 ohms and are accordingly maintained at equalpotentials, as regards "D. C. conditions whilst as regards alternatingcurrent conditions the same possess diifere'nt potentials. 6"

The deflecting potential provided by the generator- 8 is amplified inthe amplifier tube 9, preferably a pentode, and then applied to thelower deflecting plate 4 over a condenser ill.

The control grid I2 of the phase-reversing tube 1 0 l3, which'preferablyis also in the form of a pentode, is connected with the anode resistancell of the pentode 9. The deflecting potential of reverse phase thusproduced is applied over the condenser I l and the line IE to the plate6. tap at the anode resistance. is so selected that the defiectingpotentials of reverse phase taken from the two pentodes have equalamplitudes. The anode potential for both pentodes is taken fromthe samepotential source It and is'ap b plied to the pentodes over thepotentiometer ll. Since the alternating potentials occurring in theanode circuits of the two pentodes are in this manner causedcornpletelyto compensate each other, it is rendered possible by the arrangement aaccording to the invention to reduce to a minimum, or possibly even omitentirely, special steadying means otherwise always necessary in theanode circuit.

The condenser l8 may be selected at .5 mi., 30 the condensers l 9 and 20each at 1 mi. the resistances 2|, 22, 23 at .1 megohm, the parts of theresistance IT at the two sides of the tap each at 5000 ohms, theresistance 24 at 25,000 ohms, and

the resistance 1' at .1 megohm. The resistance 1 35 should preferablyalways be small in relation to the-working resistance.-

The arrangement according to the invention is for use both in the linefrequency deflection as well as the frame frequency deflection por- 40tions.

For the line-frequency deflection portion the condensers 25, 26 and Mshould each be selectedat-1000 cm., and the two anode resistances eachat 20,000 ohms. 45

From the frame-frequency deflection portion the condensers 25, 26 and Mmay be selected preferably each at .1 mf., and the anode resistances Hand 2! each at .1 megohm. The position of the tapping point, as alreadystated, 50 is determined by the amplification of the pentodes in respectof the different frequencies, and is always selected to be such that thedeflecting potentials possess the same amplitude.

Variations of the above dimensions cited as 55 The for coupling thecontrol grid of said phaseexamples are of course possible withoutdeparting from the prinicple of the invention.

Since the frame frequency deflection portion permits of betteramplification than the line frequency deflection portion (approximately100220) it is necessary, more particularly in those cases in which thecomplete raster is transmitted by wireless, to modulate the rastertransmitter ac-' cordingly. p

It is also possible to impart difierent direct potentials to the platesand 5-, and in this man ner to accomplish that the ray in the state of.

rest emerges from the space between the plates 6 and 4 displaced at anydesired angle in relation to its direction of entry. In this manner itis possible to avoid the displacement otherwise occurring when using thesystem according to the invention, and to accomplish that the ray meetsexactly against the centre of the image screen when in the state ofrest.

I claim:

1. Connection device for operating the electr c static deflecting systemof a Braun tube comprising two outer plates and two middle plates, saiddevice consisting of a circuit comprising means for'producing analternating voltage, an

amplifier tube having a cathode, an anode, and

a control grid, means for applying said alternating voltage to saidcontrol, grid, a first anode resistance having one of its ends directlyconnected to said anode, so that an alternating potential may be takenfrom this end, a tap on said anode resistance, a phase-reversingtubehaving a cathode, an anode, and a control grid, means 2. Circuitcomprising meansfor producing an alternating scanning potential'relativeto a fixed potential, means for producing in relation to the same fixedpotential a further alternating potential equal in amplitude to saidscanning potential but reversed in phase with respect to said scanningpotential, means to apply one of said two alternating potentials to oneof said outer plates, and means to apply the other one of said twoalternating potentials to one of said middle plates, a circuitcomprising means for producing an alternating voltage, an amplifier tubehaving a cathode, an anode, and a control grid, means for applying saidalternating voltage to said'control grid, a first anode resistancehaving one of its ends directly connected to said anode, so that analternating potential may be taken from this end, a tap on said anoderesistance, a phasereversing tube. having a cathode, an anode, and acontrol grid, means for coupling the control grid of saidphase-reversing tube to said tap, a second anode resistance having oneof its ends directly connected to the anode of said phase reversing tubeso that a further alternating potential reversed in phase with respectto the first said alternating potential may be taken from. the lastmentioned end, a common anode voltage source, for supplying the anodesof both said am,- plifier and phase reversing 'tubes with anodevoltages, a common resistance having one of its ends connected to thesaid'first anode resistance,

and its other end to said second anode resistance, a point of saidcommon resistance intermediate of its ends being connected to thepositive end of said anode voltage source, the cathode of said amplifierand phase-reversing tubes being maintainedat the potential of thenegative end of saidanode voltage source, means for adjusting said tapto make the amplitude of the second alternating potential relatively toa fixed potential equal to the amplitude of the first said alternatingpotential relatively to the same said fixed potential, means forcoupling one of said alternating potentials to one of said outer platesand means for coupling the other one of said alter hating potentials toone of said middle plates.

3. The invention as claimed in claim 1, including means for adjustingsaid intermediate point of said common resistance to cause thealternating anode voltages to compensate each other in the anode feedline.

KURT SCI-ILESINGER.

